全文获取类型
收费全文 | 61361篇 |
免费 | 4556篇 |
国内免费 | 4536篇 |
专业分类
化学 | 28950篇 |
晶体学 | 767篇 |
力学 | 1221篇 |
综合类 | 765篇 |
数学 | 16975篇 |
物理学 | 21775篇 |
出版年
2023年 | 448篇 |
2022年 | 729篇 |
2021年 | 1628篇 |
2020年 | 1226篇 |
2019年 | 1541篇 |
2018年 | 1336篇 |
2017年 | 1472篇 |
2016年 | 1710篇 |
2015年 | 1704篇 |
2014年 | 2585篇 |
2013年 | 4094篇 |
2012年 | 2932篇 |
2011年 | 3684篇 |
2010年 | 3070篇 |
2009年 | 3959篇 |
2008年 | 4113篇 |
2007年 | 4494篇 |
2006年 | 3503篇 |
2005年 | 2521篇 |
2004年 | 2298篇 |
2003年 | 2139篇 |
2002年 | 1951篇 |
2001年 | 1746篇 |
2000年 | 1355篇 |
1999年 | 1269篇 |
1998年 | 1192篇 |
1997年 | 909篇 |
1996年 | 996篇 |
1995年 | 872篇 |
1994年 | 862篇 |
1993年 | 826篇 |
1992年 | 727篇 |
1991年 | 533篇 |
1990年 | 438篇 |
1989年 | 374篇 |
1988年 | 342篇 |
1987年 | 286篇 |
1986年 | 290篇 |
1985年 | 421篇 |
1984年 | 325篇 |
1983年 | 198篇 |
1982年 | 350篇 |
1981年 | 520篇 |
1980年 | 499篇 |
1979年 | 501篇 |
1978年 | 410篇 |
1977年 | 313篇 |
1976年 | 269篇 |
1974年 | 91篇 |
1973年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
21.
Jamil Chaker 《Mathematische Nachrichten》2019,292(11):2316-2337
We consider systems of stochastic differential equations of the form for with continuous, bounded and non‐degenerate coefficients. Here are independent one‐dimensional stable processes with . In this article we research on uniqueness of weak solutions to such systems by studying the corresponding martingale problem. We prove the uniqueness of weak solutions in the case of diagonal coefficient matrices. 相似文献
22.
Shai Shechter 《Journal of Pure and Applied Algebra》2019,223(10):4384-4425
Let be a complete discrete valuation ring with finite residue field of odd characteristic, and let G be a symplectic or special orthogonal group scheme over . For any let denote the ?-th principal congruence subgroup of . An irreducible character of the group is said to be regular if it is trivial on a subgroup for some ?, and if its restriction to consists of characters of minimal -stabilizer dimension. In the present paper we consider the regular characters of such classical groups over , and construct and enumerate all regular characters of , when the characteristic of is greater than two. As a result, we compute the regular part of their representation zeta function. 相似文献
23.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates. 相似文献
24.
Yasuhito Tanaka 《Operations Research Letters》2019,47(5):406-409
We study a dynamic free-entry oligopoly with sluggish entry and exit of firms under general demand and cost functions. We show that the number of firms in a steady-state open-loop solution for a dynamic free-entry oligopoly is smaller than that at static equilibrium and that the number of firms in a steady-state memoryless closed-loop solution is larger than that in an open-loop solution. 相似文献
25.
Bilender P. Allahverdiev 《Mathematical Methods in the Applied Sciences》2019,42(1):229-236
In this study, maximal dissipative second‐order dynamic operators on semi‐infinite time scale are studied in the Hilbert space , that the extensions of a minimal symmetric operator in limit‐point case. We construct a self‐adjoint dilation of the dissipative operator together with its incoming and outgoing spectral representations so that we can determine the scattering function of the dilation as stated in the scheme of Lax‐Phillips. Moreover, we construct a functional model of the dissipative operator and identify its characteristic function in terms of the Weyl‐Titchmarsh function of a self‐adjoint second‐order dynamic operator. Finally, we prove the theorems on completeness of the system of root functions of the dissipative and accumulative dynamic operators. 相似文献
26.
This paper develops a framework to deal with the unconditional superclose analysis of
nonlinear parabolic equation. Taking the finite element pair $Q_{11}/Q_{01} × Q_{10}$ as an example,
a new mixed finite element method (FEM) is established and the $τ$ -independent superclose
results of the original variable $u$ in $H^1$-norm and the flux variable $\mathop{q} \limits ^{\rightarrow}= −a(u)∇u$ in $L^2$-norm are deduced ($τ$ is the temporal partition parameter). A key to our analysis is an
error splitting technique, with which the time-discrete and the spatial-discrete systems are
constructed, respectively. For the first system, the boundedness of the temporal errors is obtained. For the second system, the spatial superclose results are presented unconditionally, while the previous literature always only obtain the convergent estimates or require
certain time step conditions. Finally, some numerical results are provided to confirm the
theoretical analysis, and show the efficiency of the proposed method. 相似文献
27.
28.
29.
30.
The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance. 相似文献